Suspended scaffolding



April 28, 1964 FACKLER ETAL 3,130,813

SUSPENDED SCAFFOLDING Filed June 8, 1961 5 Sheets-Sheet 1 I Jnvenfars: KAKL FAG/(LE1? ALFRED WI6K$FLOG ATTORNEY April 28, 1964 Filed June 8, 1961 K. FACKLER ETAL SUSPENDED SCAFF'OLDING 5 Sheets-Sheet 2 177 I I I [77 2mm I Fig. 5

ATTOENEY April 28, 1964 FACKLER ETAL 3,130,813

SUSPENDED SCAFFOLDING Filed June 8, 196i 5 Sheet Sheet 3 Jnvenfors: KAEL FACKLEE ALFRED WISSFZOG ATTOE/VEY April 28, 1964 Filed June 8, 1961 5 Sheets-Sheet 4 Jnven/ors: KARL FAG/(L 5/? AL FEED WE/SSFZOG April 28, 1964 FACKLER ETAL 3,130,813

SUSPENDED SCAFFOLDING Filed June 8, 1961 5 Sheets-Sheet 5 Fig. 9

Jnvenfars: KARL FAC/(LEE ALI-FED WEISS/Q06 United States Patent Germany Filed lune 8, 1961, Ser. No. 115,701 5 Claims. (Cl. 18236) The present invention relates to scaffolds in general, and more particularly to a suspended scaffolding which may be utilized for providing access to the walls of tall buildings. Still more particularly, the invention relates to a suspended scaffolding which may be utilized for inspection, repair, painting or cleaning of side walls on tall buildings including the lateral, front and rear walls of such structures.

An important object of the invention is to provide a suspended scaffolding which is constructed and assembled in such a way that its platform may be readily and conveniently advanced longitudinally and/or vertically along the side walls of a building structure and that the platform may be conveniently lifted onto the roof and away from the side walls, thus enabling the workmen to enter or leave the platform while the latter is located at a safe distance from the roof edge.

Another object of the invention is to provide a suspended scaffolding of the just outlined characteristics whose platform or cab may be moved into close proximity of a facade or another side wall even though the building is provided with a cornice which projects beyond the side Wall and which would normally prevent a suspended platform from being moved into close proximity of the side wall.

A further object of the invention is to provide a suspended scaffolding whose main supporting structure which is normally mounted for travel on the roof of the building need not be rotated in order to transfer the platform onto the roof and into a position to be conveniently reached or evacuated by the workmen at a safe distance from the roof edge.

An additional object of the invention is to provide a suspended scaffolding wherein the platform may be suspended on comparatively short supporting arms so that the tilting forces acting on the main supporting structure are comparatively small, wherein the platform may be rapidly and conveniently moved closer to or further away from the side walls of a building, which may be completely concealed from an observer standing on the street when the platform is within the confines of a building, which may be safely repaired without any danger to the workmen, and whose platform may be moved about to selectively advance along the facade, along the rear wall or along the lateral walls of a building.

With the above objects in view, the invention resides in the provision of a suspended scaffolding which is mounted on a supporting surface located at an elevation from the ground and is adjacent to a side wall of a building, the scaffolding comprising a main supporting member or truck which is mounted on spaced guideways provided on the supporting surface of the building and extending along the side wall, supporting arms pivotally connected to the truck so as to be turnable about a horizontal axis which is preferably parallel with and located between the guideways, a platform which is suspended on the supporting arms at a point distant from the truck, means for pivoting the platform with the supporting arms between a first position in which the platform is located above and is preferably deposited on the supporting surface of the building at one side of the truck, and a second position in which the platform is moved outwardly and beyond the supporting surface and may be lowered and 3,l3@,8l3 Patented Apr. 28, 1964 "ice raised along the side wall. Depending on the extent to which the arms are pivoted outwardly and beyond the supporting surface of the building structure, the platform may be moved closer to or further away from the side wall and, while the arms move between said positions, the platform describes an arc above the truck so that, if desired, the platform may be arrested in a position in which it is located above the truck and may be entered from the truck.

Certain other features of the invention reside in the special construction of a truck-mounted winch which is used for raising and lowering the platform along a side wall, in the provision of an automatic speed-responsive brake for the winch, in the provision of a specially constructed truck which may be moved along arcuate guideways, and in the provision of specially configurated supporting arms for the platform enabling the platform to be lowered beneath a cornice or another projection which extends outwardly beyond the supporting surface and overhangs a side wall of the building.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will bet best understood from the following detailed description of certain specific embodiments with reference to the accompanying drawings, in which: 1

FIG. 1 is a schematic side elevational view of a suspended scaffolding embodying oneform of the invention, the platform and its supporting arms being shown in three different positions;

FIG. 2 is a vertical section through the scaffolding as seen in the direction of the arrows from the line AB of FIG. 1;

FIG. 3 is an enlarged fragmentary section taken along the line C-D of FIG. 2, as seen in the direction of the arrows;

FIG. 4 is a schematic side elevational view of a modified suspended scaffolding, showing the platform and one of its supporting arms in two different positions;

FIG. 5 is an enlarged fragmentary elevational view of a winch forming part of the suspended scaffolding;

FIG. 6 is an enlarged end elevational view of a device for pressing the cable against a drum which constitutes a component part of the winch shown in FIG. 5;

FIG. 7 is an enlarged section taken along the line E--F of FIG. 6, as seen in the direction of arrows;

FIG. 8 is an enlarged end elevational view of an automatic safety brake for the cable drum;

FIG. 9 is a partly elevational and partly sectional view of a modified truck for the scaffolding which is capable of travelling along arcuate guideways; and

FIG. 10 is a section taken along the line GH of FIG. 9, as seen in the direction of arrows.

Referring now in greater detail to the illustrated embodiments, and first to FIGS. 1 and 2, there is shown a building structure 1 which is formed with a roof or terrace having a preferably horizontal supporting surface 1 for guideways here shown as a pair of spaced rails 2. The rails 2 serve as a means for guiding pairwise arranged wheels 3 of a main supporting element or truck 3 which forms part of the improved suspended scaffolding 1. The truck 3 carries a horizontal main shaft 4 whose axis is parallel with and which is located between the rails 2. This main shaft 4 swingably supports two spaced supporting arms or beams 5 for a platform 6, this platform being shown in the form of a nearly fully enclosed cab or cage whose side facing the side wall, eg the facade la of the building 1 is assumed to be open so that the workman or workmen occupying the platform 6 may conveniently paint, clean, repair or perform another type of work on the facade 1a. The platform 6 is suspended on cables 9 which pass about deflecting elements in the form of sheaves 19, the latter swingably supported in a transverse connecting member 7 which extends between the free end of the arms and is distant from the truck 3. The means for pivoting the arms 5 about the axis of the main shaft 4 may comprise a reversible motor 4a which is preferably mounted in the truck 3' and a suitable transmission 4-12 which is indicated schematically by a dot-dash line. The motor 4a may be operated by remote control by means which are provided on or in the platform 6.

As shown in FIG. 2, the length of the supporting arms 5 is sufiicient to permit pivotal movements of the platform 6 in an arc between and even beyond the phantomline and dotted-line positions of FIG. 1, provided that the platform is lifted reasonably close to the transverse connecting member 7. When the platform assumes its phantom-line position, it may be readily raised or lowered, along the facade la to a desired elevation and, by causing the truck 3' to move along its rails 2, the operator or operators may move the suspended scaffolding to any esired position with respect to the facade of the building. On the other hand, when the motor 4a is caused to pivot the arms 5 and the platform 6 to their brokenline positions, the operator or operators may conveniently enter or leave the platform without any danger to thei safety because the platform is located at a safe distance from the roof edge, i.e. from the facade 1a, and is separated from the facade by the truck 3'. Owing to the provision of elongated supporting arms 5, the operator or operators may swing the platform between the brokenline and phantom-line positions of FIG. 1 without it being necessary to turn the truck 3 about a vertical axis as is customary in certain suspended scaffoldings of presently known design. The winch or winches and their motor means for winding and unwinding the cables may be accommodated in the platform 6 or in the truck 3 and may be operated by controls provided in or on the platform so that the operator or operators may fully control the scaffolding not only to raise and to lower the platform but also to swing the raised platform in an arc between the phantom-line and broken-line positions of FIG. 1 to the opposite sides of the truck 3'.

FIG. 3 illustrates in greater detail the configuration of the transverse supporting member 7 and shows a sheave 19 for a cable 9 which sheave is swingably supported in the member 7. The member 7 is of arcuate cross-section and defines an internal space which opens downwardly toward the platform and accommodates a bracket 11 whose pivot pin 11a swingably supports a bail llda for the shaft Nb of the sheave ill. The pin 11:: is parallel with the axis of the member 7 and the shaft 1% is perpendicular thereto. It will be readily understood that the transverse supporting member 7 may be omitted in its entirety and that the sheaves ft for the cables 9 may be secured to or mounted in the free ends of the arms 5, if desired. In such instances, the cables 9 may be led through the arms 5 so that only that portion of each cable is exposed which extends between the free ends of the arms and the platform. The angle alpha indicates in FIG. 3 the extent to which the bails 10a must be free to pivot about the respective pins 11a to properly support the cables 9 in and between the phantom-line and broken-line positions of the platform 6.

FIG. 4 illustrates a modified suspended scaffolding II which comprises a truck 3' having wheels 3 mounted for travel along spaced rails 2, the latter supported by the horizontal upper surface of a roof or terrace forming part of a building Hi1. This building has a forwardly extending projection or cornice 8 which extends well beyond the surface 1 and overhangs the facade la. In order to enable the platform or cabin 6 to move into close proximity of the facade Ila, the scaffolding II com- All prises a pair of slightly different supporting arms 5 (only one shown) which assume the form of hooks and whose end portions 5a which are distant from the main shaft 4 are bent forwardly so that these end portions may extend beneath the cornice 8 to move the cables 9 to the broken-line positions 9 and to move the platform into immediate proximity of the facade 1a when the arms are swung in anticlockwise direction, as viewed in FIG. 4.

It will be readily understood that the platform 6 and its arms 5 may be swingable clockwise beyond their full-line positions of FIG. 4 so that the platform is close to the surface 11 and that a Workman may conveniently enter or leave the same. Alternately, the truck 3 of the scaffolding II may be provided with one or more steps 3s so that the operator may enter the platform by ascending the step or steps 3s while the platform assumes the full-line position of FIG. 4.

The suspended scaffolding of our invention may be conveniently adjusted to locate the platform 6 at any desired distance from the facade or another side wall of a building structure. All that is necessary is to change the inclination of the arms 5 or 5' so as to move the platform toward and away from the building. For example, and referring to FIG. 1, the platform 6 may be moved further away from the facade 1:1 by operating the motor 4a in a direction to swing the arms 5 in anticlockwise direction beyond the phantom-line position. Also, the motor 4a may swing the arms 5 beyond the broken-line position so that the underside of the platform 6 comes to rest on the surface 1. All repairs to the scaffolding may be carried out while the platform is swung to a position above and within the confines of the building structure so that the danger to workmen carrying out the repairs is fully eliminated. When the platform 6 assumes the broken-line position of FIG. 1, the entire scaffolding is completely concealed from persons standing on the street in front of the building 1.

Particularly if the controls for various movements of the scaffolding are provided in or on the platform, the personnel occupying the platform may readily operate the scaffolding in all situations which may arise when the scaffolding is in actual use. For example, the workmen may steer the platform 6 clear of any obstructions while the platform performs a horizontal or a vertical movement along the facade or along another side wall of the building. Thus, the workmen may avoid balconies, open windows, flagpoles, projections of all kinds, advertising and lighting devices which may project beyond a wall, and all other types of obstructions. In other words, the movability of the platform in three different directions, namely, toward and away from the side wall, horizontally along the side wall, and vertically along the side wall, enables an operator to avoid all visible as well as all unforeseen and suddenly emerging obstructions. In the event that a strong gale would tend to swing the platform, the operator merely operates the motor 4a in a direction to move the platform into actual abutment with the facade or another side wall and to thereby prevent any further swinging.

The platform may be utilized for transporting and mounting large objects on the side walls of a tall building. Thus, a large sign, poster, light fixture, window frame, flagpole or the like may be placed into or attached to the platform while the latter assumes the broken-line position of FIG. 1, and the platform is then swung outwardly toward and even beyond the phantom-line position to descend along the side wall and to move the object to a desired position where it can be secured to the building by one or more workmen riding along in the platform.

Referring to FIG. 5, there is shown a winch assembly for a cable 9 which is assumed to be mounted in the truck 3' and which comprises a grooved rotary cable drum 1?), an externally threaded rotary spindle 15 which is parallel with the drum 13, an internally threaded member in the form of a nut 14 which meshes with and is adapted to travel back and forth along the spindle 15 and which supports a guide member or sheave -12 for the cable 9, and means 1618 for drivingly connecting the drum 13 with the spindle 15. The cable 9 has one of its ends anchored in the drum 13, thereupon passes about the sheave 12 toward the deflecting element (see FIG. 3), and has its other end connected to the platform 6. The spindle and its nut 14 constitute a so-called multiplereturn device for the cable 9 and insure that the cable is uniformly distributed about the periphery and in the groove 13a of the drum 13 when the latter is rotated in a direction to collect the cable and to thereby lift the platform 6 to the phantom-line position of FIG. 1. In the embodiment of FIG. 5, the means for drivingthe spindle 15 and for thereby moving the nut 14 back and forth along the spindle in response to clockwise or anticlockwise rotation of the drum 13 comprises a sprocket 17 which is coaxially secured to the drum and is drivingly connected with the sprocket 16 of the spindle 15 by a chain 18. It will be understood that the sprockets 16, 17 and the chain 18 may be respectively replaced by suitable pulleys and by a V-belt, if desired. The transmission ratio of the sprockets 17, 16 and the pitch of threads on the spindle 15 are such that the spindle will cause the nut 14 to move at a rate of speed corresponding to the rate of speed at which the cable 9 is being collected on or paid out by the drum 13. The other end of the drum 13 may support the second cable 9 (not shown), and the spindle 15 may be provided with a second nut for a second sheave to guide the second cable 9 on its way toward the platform 6.

FIG. 6 is an end View of the cable drum 13 and of the spindle 15, further showing a device for pressing the cable 9 against the periphery of the drum and for thereby maintaining the cable in its spiral groove 13a, see FIG. 7. This device comprises a bell crank lever 20 which is pivotably supported by a bracket 20a secured to and movable with the nut 14, a spring 21 which is connected with one arm of the lever 20 and with a second bracket 21a secured to the nut 14 to bias the other arm of the bell crank lever in a direction toward the periphery of the drum 13, and a pressing roller 19 which is secured to the bifurcated second arm of the bell crank lever 20 and is formed with a peripheral recess 19a adapted to receive a portion of the cable 9 and to retain the cable in its groove 13a. The nut 14 carries a bail 14a for the shaft of the sheave 12. Since the spring-biased roller 19 travels with the nut 14, it is always in proper position to resiliently press the last convolution of the cable 9 against the drum 13 and to prevent improper winding of cable onto this drum. In addition, the roller 19 prevents a slackening of the cable such as could cause a sudden descent of the platform 6.

FIG. 8 illustrates a safety brake for the drum 13. This brake is of the lever and strap type including a braking member or strap 29 having its first end secured to a bracket 2% on the truck 3' and its second end secured to a lever 23 which is fulcrumed to the truck, as at 28a, and which is permanently biased by resilient means here shown as a spring 28 so as to force the brake lining of the strap 29 against a peripheral portion of the drum 13. The lever 28 may be pivoted against the bias of the spring 28' by an electromagnetic device including a coil 27 and an armature 27a whose rod is articulately connected with the lever 28. The electric circuit 26 of the coil 27 includes a source 26a of electrical energy and an automatic speed-responsive switch which opens the circuit in response to a predetermined rotational speed of the drum v1.3. The switch 25 may comprise a say centrifugal circuit breaker, not shown, which is driven by a gear 23, the latter being driven by a flexible element in the form of a chain 24 which passes about a gear 22 coaxially secured to the drum I13. The circuit 26 is normally completed so that the normally energized coil 27 draws its armature 27a in upward direction, as viewed 'the spring 28. However, when the drum :13 reaches a predetermined rotational speed, the switch 25 automatically opens thecircuit 26 and deener-gizes the coil 27 so that the spring 28 may pivot the lever 23 in clockwise direction to thereby apply the brake lining of the strap 29 against the periphery of the drum 13 and to slow down or to arrest the drum. The gears 22, 23 and the chain 24 constitute a step-up transmission for driving the switch 25 at a speed which is proportional with and is normally higher than the rotational speed of'the drum .13.

Referring finally to FIGS. 9 and 10, there is shown a special truck 3" which is constructed in such a way that its wheels 36 may travel along arcuate portions of the rails 2" (only one shown). The truck 3 comprises a chassis 30 which supports a main shaft 31 for the arms of the non-illustrated platform. The chassis 30 supports pairwise arranged frame members 32 each of which is swingable about a vertical pivot axis defined by the aligned pairs of trunnions 33 which are articulately mounted in a suitable frame forming part of the chassis 30. The outer ends of the axle members 32 respectively support two vertical pivot members 34 for the housings 35 of the wheels 36. The wheels 36 are mounted for travel along the upper sides of the rails 2". I In addition, each Wheel housing 35 supports two pairs of lateral rollers 37 'each 'pair of which engages a side of the rail 2" to properly guide the truck 3" in a curve and to prevent a tilting of the truck under the weight of the platform. The rollers 37 may be configurated in such a way that they actually embrace'portions of the rails 2"a'nd prevent a lifting of the wheels 36- away from the rails. As clearly shown in FIG. 10, the radius of curvature of the rails may be rather small because the frame members 32 are pivotable about the vertical pivot axes of the aligned tmnnions 33 and because the wheel housings 35 are pivotable about the vertical pivot axes of the members 34 so that the wheels 36 may readily follow the curvature of the rails.

The construction of a truck 3 in the manner shown in FIGS. 9 and 10 is of particular advantage because it is possible to utilize a single suspended sca'ffoldingalong the front, lateral and/ or rear walls of a building. The truck travels along the corners of the building while moving on arcu-ate rails and it is not necessary to withdraw the platform within the confines of the building because the distance between the platform and the side walls may be varied so that the platform will move about the corners even if it is located at a level below the truck and below the surface 1.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. The combination with a building structure having side wall means and a substantially horizontal supporting surface located at an elevation above the ground, of a suspended scaflolding comprising spaced parallel guideways provided on said surface and extending along said side wall means, a truck having wheels mounted on said guideways, a horizontal main shaft mounted on said truck and located between and substantially parallel with said guideways, a pair of spaced supporting arms having first ends connected with said shaft and second ends spaced from said truck, transverse connecting means extending between and connected with the second ends of said arms, a platform, deflecting means mounted on said transverse connecting means, winch means provided on said truck and comprising cable means passing over said defleeting means and having ends connected with said platform so as to raise and to lower the platform when re spectively collected and paid out by said winch means, said winch means further comprising rotary drum means mounted on said truck and connected with said cable means, externally threaded spindle means mounted on said truck and substantially parallel with said drum means, internally threaded means meshing with said spindle means, sheave means mounted on said internally threaded means, and means for drivingly connecting said drum means with said spindle means so that said internally threaded means travels back and forth along said spindle means when said drum means rotates in clockwise and anticlockwise directions, said cable means passing from said drum means over said sheave means and to said deflecting means, and means for pivoting said arms and the platform about the axis of said shaft between a first position in which the platform is moved outwardly and beyond said surface at one side of said truck and may be raised and lowered along said side wall means, and a second position in which the platform is located above said surface and at the other side of said truck after moving in an arc above the truck whereby the platform may be accessible to a person standing on the supporting surface for mounting said platform from the supporting surface, and the supporting surface may be accessible to a person standing on said platform for alighting from said platform onto the supporting surface.

2. A combination as set forth in claim 1, further comprising spring-biased means mounted on said internally threaded means for pressing said cable means against the periphery of said drum means.

3. A combination as set forth in claim 2, wherein said spring biased means is a roller formed with a peripheral recess for partially receiving said cable means.

4. The combination of a building structure having side wall means and a supporting surface located at an elevation above the ground, with a suspended scaffolding comprising main supporting means supported by said surface, supporting arm means pivotally connected with said main supporting means, platform means suspended on said arm means at a point distant from said main supporting means, means for pivoting said arm means between a first position in which the platform means is located above said surface whereby said platform means is accessible to a person standing on the supporting surface for-ascending the platform means from the supporting surface and the supporting surface is accessible to a person standing on said platform means for alighting from said platform means onto the supporting surface, and a second position in which said platform means is moved outwardly beyond said surface and is adjacent to said side wall means, and winch means for raising and lowering said platform means along said side wall means, said winch means comprising a cable drum rotatably mounted in said main supporting means and automatic braking means for said cable drum, said braking means comprising a braking member adjacent to said drum, means for permanently biasing asid braking mem- .ber into braking engagement with said drum, normally energized electromagnetic means for moving said braking member away from said drum, and switch means connected in the circuit of said electromagnetic means, said switch means being operatively connected with and being responsive to a predetermined rotational speed of said drum for opening the circuit of and for dc-energizing said electromagnetic means so that said biasing means may move the braking member into braking engagement with said drum in response to said predetermined rotational speed.

5. A combination as set forth in claim 4, wherein the operative connection between said drum and said switch means comprises a step-up transmission for driving the switch means at a speed higher than the rotational speed of said drum.

References Cited in the file of this patent UNITED STATES PATENTS 218,467 Apsey Aug. 12, 1879 323,924 Evers Aug. 11, 1885 799,865 McConnell Sept. 19, 1905 1,100,577 Lindncr June 16, 1914 1,412,383 Barrow Apr. 11, 1922 1,416,775 Bauer May 23, 1922 2,178,956 Dyer Nov. 7, 1939 2,321,780 Tondeur June 15, 1943 2,657,011 Slonneger Oct. 27, 1953 2,950,086 Abraham Aug. 23, 1960 FOREIGN PATENTS 509,863 Italy Jan. 18, 1955 1,077,856 Germany Mar. 17, 1960 

1. THE COMBINATION WITH A BUILDING STRUCTURE HAVING SIDE WALL MEANS AND A SUBSTANTIALLY HORIZONTAL SUPPORTING SURFACE LOCATED AT AN ELEVATION ABOVE THE GROUND, OF A SUSPENDED SCAFFOLDING COMPRISING SPACED PARALLEL GUIDEWAYS PROVIDED ON SAID SURFACE AND EXTENDING ALONG SAID SIDE WALL MEANS, A TRUCK HAVING WHEELS MOUNTED ON SAID GUIDEWAYS, A HORIZONTAL MAIN SHAFT MOUNTED ON SAID TRUCK AND LOCATED BETWEEN AND SUBSTANTIALLY PARALLEL WITH SAID GUIDEWAYS, A PAIR OF SPACED SUPPORTING ARMS HAVING FIRST ENDS CONNECTED WITH SAID SHAFT AND SECOND ENDS SPACED FROM SAID TRUCK, TRANSVERSE CONNECTING MEANS EXTENDING BETWEEN AND CONNECTED WITH THE SECOND ENDS OF SAID ARMS, A PLATFORM, DEFLECTING MEANS MOUNTED ON SAID TRANSVERSE CONNECTING MEANS, WINCH MEANS PROVIDED ON SAID TRUCK AND COMPRISING CABLE MEANS PASSING OVER SAID DEFLECTING MEANS AND HAVING ENDS CONNECTED WITH SAID PLATFORM SO AS TO RAISE AND TO LOWER THE PLATFORM WHEN RESPECTIVELY COLLECTED AND PAID OUT BY SAID WINCH MEANS, SAID WINCH MEANS FURTHER COMPRISING ROTARY DRUM MEANS MOUNTED ON SAID TRUCK AND CONNECTED WITH SAID CABLE MEANS, EXTERNALLY THREADED SPINDLE MEANS MOUNTED ON SAID TRUCK AND SUBSTANTIALLY PARALLEL WITH SAID DRUM MEANS, INTERNALLY THREADED MEANS MESHING WITH SAID SPINDLE MEANS, SHEAVE MEANS MOUNTED ON SAID INTERNALLY THREADED MEANS, AND MEANS FOR DRIVINGLY CONNECTING SAID DRUM MEANS WITH SAID SPINDLE MEANS SO THAT SAID INTERNALLY THREADED MEANS TRAVELS BACK AND FORTH ALONG SAID SPINDLE MEANS WHEN SAID DRUM MEANS ROTATES IN CLOCKWISE AND ANTICLOCKWISE DIRECTIONS, SAID CABLE MEANS PASSING FROM SAID DRUM MEANS OVER SAID SHEAVE MEANS AND TO SAID DEFLECTING MEANS, AND MEANS FOR PIVOTING SAID ARMS AND THE PLATFORM ABOUT THE AXIS OF SAID SHAFT BETWEEN A FIRST POSITION IN WHICH THE PLATFORM IS MOVED OUTWARDLY AND BEYOND SAID SURFACE AT ONE SIDE OF SAID TRUCK AND MAY BE RAISED AND LOWERED ALONG SAID SIDE WALL MEANS, AND A SECOND POSITION IN WHICH THE PLATFORM IS LOCATED ABOVE SAID SURFACE AND AT THE OTHER SIDE OF SAID TRUCK AFTER MOVING IN AN ARC ABOVE THE TRUCK WHEREBY THE PLATFORM MAY BE ACCESSIBLE TO A PERSON STANDING ON THE SUPPORTING SURFACE FOR MOUNTING SAID PLATFORM FROM THE SUPPORTING SURFACE, AND THE SUPPORTING SURFACE MAY BE ACCESSIBLE TO A PERSON STANDING ON SAID PLATFORM FOR ALIGHTING FROM SAID PLATFORM ONTO THE SUPPORTING SURFACE. 